Gametes of a green alga, Ulva pertusa Kjellman exhibited chemotactic responses to a variety of concentrations of the chemical nutrients and thallus extracts. Chemotasix was measured by counting the number of gametes that swam into glass capillary tubes with artificial seawater containing the chemical or biological agents relative to the number of that swam into control tubes with artificial seawater only. Similar chemotactic effects were observed between one and four day-old preparations of U. pertusa gametes. Positive chemotaxis has been observed with nitrate concentrations of 0.01, 0.1 M and with phosphate concentration of 1 m M. Low concentrations of nitrate (0.001M) and phosphate (0.01M) elicited negative chemotaxis. There was no significant chemotactic responses at 0.1 mM of phosphaste. When different concentrations of maternal thalli extracts (5, 10, 25, 50, 100 g FW/500 ml ASW)were given gametes showed negative chemotactic responses except for concentration of 0.5 g FW/500 ml ASW where there was no effect. All concentrations of thallus extracts (0.5, 5, 50 g FW/500 ml ASW) of the red alga Pachymeniopsis sp. had no effect on chemotactic responses of U. pertusa gametes.

This study was investigated to phytoplankton community and trophic state by LTSI in Lake Tokdong from November 1990 to October 1992. Phytoplankton community was identified total 352 taxa, which was composed of 320 species, 28 varieties and 4 forms, belong to 117 genera, 37 families, 6 suborders, 14 orders and 7 classes. The standing crops of phytoplankton were raged from 4.3 ×10⁴cells/l to 4.5× cells/l. The dominant species were Aulacoseira ambigua, A. distans var. alpigena, A. granulata, Cyclostephanos dubius, Cyclotella pseudostelligera, Chlamydomonas globosa, Tetraedron minimum and Monoraphidium contortum. LTSI were ranged from 3.9 to 11.4 and their trophic states were higher values than 10 from July to September 1991, and the trophic states of these times were hypertrophy. This tended to be overestimation by the allochthonous suspensoids(silt or clay). Therefore, This lake was assessed from mesotrophic to eutrophic states during investigation

Succession and community structure of benthic marine algae of Inchon Dock, an enclosed artificial dock in the western coast of Korea, wee investigated qualitatively and quantitatively. A total of 52 species was identified in this area : 22 blue-greens, 15 greens, 7 browns and 8 reds. Species composition and biomass of benthic algal community in Inchon Dock were quite different from the rocky shore community. Dominant species determined by biomass and frequency was Polysiphonia morrowii, and subdominant species was Lyngbya semiplena and Lyngbya lutea. During the study, benthic algal community was perturbated completely by red tide(causative species: Mesodinium rubrum, ciliate) in June 1990, and recolonization process had begun thereafter. As a result, the succession pattern of benthic algal community of closed dock marine ecosystem staged at channelling succession phase. It was concluded that a normal community structure could be attained after 10 months since the ecosystem was disturbance. Succession pattern was revealed as a seasonal cyclic succession. Multiple regression analysis was applied on benthic algal species and associated physico-chemical environmental factors in Inchon dock. Among the 15 factors, water temperature, precipitation, salinity, nitrite-nitrogen and nitrate-nitrogen appeared to be important environmental factors for the distribution of benthic algae.

The bioconcentration potential land effects of fluoranthene, one of the polycyclic aromatic hydrocarbons (PAHs), on the growth of Porphyra conchocelis were examined. The fluoranthene concentration in conchocelis was 3 to 5 times as much as the concentration of the culture medium when exposed at 0.01-1 ppm. At 10 ppm fluoranthene, however, the tissue concentration did not exceed the one of the medium. Usually the highest concentration was reached at week 2-3. The growth of conchocelis, estimated by tissue weight or chlorophyll α and carotenoids contents, was not influenced by 0.01-0.1 ppm fluoranthene exposed. With higher concentrations of fluoranthene, 1-10 ppm, chlorophyll α and carotenoids contents were markedly reduced after 4-5 weeks of exposure.

The stratospheric ozone depletion due to anthropogenic activities has resulted in increasing flux of solar mid-ultraviolet radiation (UV-B; 280-320 nm) to the earth's surface and to ecologically significant depth in the ocean. Rising UV-B levels are potentially threatening organisms since UV-radiation is readily absorbed by some important biomolecules such as DNA, protein and lipids. There has been extensive documentation of adverse effects of UV-B on marine algae, which include increase in mortality, reduction in growth and photosynthetic rates, inhibition of carbon and nitrogen assimilation, destruction of photosynthetic pigments and retardation of reproductive cell motility and so on. There are adaptive ways by which UV-induced damage is mitigated. One of the mechanisms is the presence of UV-absorbing pigments (UVP). Compounds of these types have now been isolated from various marine organisms and identified as a series of mycosporine-like amino acids (MAAs). The MAAs are composed of a cyclo-hexenone ring attached with an amino acid side group. These compounds absorb in wavelengths ranging from 310 to 365 nm, spanning both UV-B and UV-A (320-400 nm) portions of the solar spectrum, but transmit photosynthetically active radiation (PAR; 400-700 nm). Seven MAAs have so far been isolated from marine macroalgae and identified as mycosporine-glycine, shinorine, porphyra-334, palythine, asterina-330, palythinol, usujirene and palythene. The role of MAAs as UV protectants is inferred from observations that their concentrations are correlated with the environmental UV fluences organisms can experience. Antarctic rhodophytes with high concentrations of UVP were more tolerant of natural and artificial UV than those with lower concentrations. However, the link between UVP levels and UV-N sensitivity is not always straightforward. In addition, the main absorption band of MAAs is well in the UV-A, thus making it difficult to assume the protective role of minimizing UV-B damage. For example, methanol extracts of two Korean macrophytes, namely Ulva pertusa (Chlorophyta) and the latter at 340 nm. The VUV-B sensitivity was however significantly differnt with the green alga being much less sensitive than the brown alga. There is also experiemtal evidence that MAAs formation is regulated not only by UV but by PAR. Although biochemical detection and characterizatio nof MAAs have been well established with a variety of macroalgae the physiological and ecoligical function of the compounds is yet largely unknown. The potential of MAAs as UV protectants remains to be determined by sustained and comprehensive studies of the compounds.